Method of washing wells



R. G. CULLEN METHOD OF WASHING WELLS Filed Deo. 11, 1956 Jan. 4, 1938.

i .Patented Jan. 4, 1938 :UNITED STATES METHOD F WASHING WELLS Rey G. Cullen, deceased, late er neusten, Tex.,

by Katherine T. Cullen, administratrix, Houston, Tex.

Application December 11, 1936, Serial No. 115,434

3 Claims.

. The present invention relates to the washing of said apparatus being shown in condition for flowoil wells and the like, particularly the washing of very deep wells.

The principal object of the invention is to provide a method and apparatus for washing wells, which will permit thorough washing of the well between the casing and tubing above the packer, so that the tubing may be elevated and lowered for any purpose subsequent to the washing operation, without delay which would be occasioned by the jamming of the tubing due to the solidification of `oil well mud between the tubing and casing above the packer. Another primary object of the invention is to le provide a method and apparatus for washing wells, which will permit the washing of the screen by currents of liquid which pass both downwardly and upwardly around the outside of the screen. Another object of the invention is to provide 2o an apparatus for bringing in `wells including a full string casing having perforations therein 1ocated with precision in the oil bearing stratum. y Another object of the invention is to provide an apparatus for washing wells, including `a screen 25 having a valve in the lower end thereof, which valve will permit flow of washing fluid both inwardly and outwardly Jthrough the bottom 013cm-,v

ing in the screen. ya further object of the invention is to provide a 3u method and apparatus for washing wells in formation having high pressure which will permit the ,well to be kept under control at all times against upward flow due to high pressure in the formation, both through the casing and through 35 the tubing. i i Another object of the invention is to provide a `methodami apparatus. for bringing in wellshav-` the well is ready to now; the packer is set, thus ing` all of theaboveadvantages, which will permit 'the iiow control equipment to be positioned 40 on the casing head after the washingoperation, so that thewell maybe controlled during itsiiow by ow control equipmentvwhich'is Ycompact and .inexpensivein constructiont- In the drawing, which illustrates `a preferred ,1. present invention, and which-.drawing is illus-v Vtrative land" in l no sense restrictive `55 vievi of the`-apparatus atthe lwer -end ofthe well,

, apparatusforv carrying out` the .methodv of the ing the well through the tubing.

Figure 3 is a partial vertical sectional view oi the lower end of the well similar to Figure 2, showing the apparatus in the condition which lit 5 assumes during the washing operations, or when the screen is being lowered into the well.

Figure 4 is a side elevational view of a part of the casing head equipment, showing the tubing head positionedlabove the casing head at the time 10 the washing operation is being performed. i

Figure 5 is a horizontal sectional view `along the line 5-5 of Figure 3. as. 1

In the present systems used in:` bringing in wells, the necessary casing is positioned in the well, after whichia tubing or liner is lowered into the well having a conventional screen and packer at the lower end thereof. When the screen is lset at the lower end of the well, the tubing is lowered to sealing position at the lower end thereof, and a washing operation is performed by owing :duid downwardly through the tubing and up around the outside of the screen, said uid passing upwardly into the casing past the packer. After this fluid traverses the length of the casing it flows outwardly through the casing head side outlets to the slush pits. Usually, a one- Way valve is provided at the lower endlof'the screen, which valve permits the outward flow of washing uid, but prevents the inward flow of fluid into the screen, thus insuring that when the well is ready for ilowing, all of the oil will pass through the perforations in the screen rather than through the bottom opening thereof. v In this conventional method of bringing' in 35 Wells, after'the washing operation has been performed and the screen is thoroughly cleaned, and

closing off the flow channel through the'lower lend of the casing between the interior thereof-and 40 theouter wall of the tubing, and when the tubing is elevated to sewing position, new `wiuftake place through the `screen `and upwardly through tnetupma Y f Y In very deepwells, and whenpracticing the' 45 Vsleevefmentienen methederlwashingga eenslderable amount of partially mud-laden uldwill be retained within the ,casing betwenflthe. inner l wall thereof andthe outer vwall of the tubingabove the .packer,fafterV the` latter has been` `sets After the setting ofthe packer, the mud in thisuid .,willzsettlajand an accumulation ofumud and sedi- -fment will' collect around the.. tubing abovegqthe packerythisfsediment being in a more orlessisolid;

condition depending on the length of time which has elapsed since the setting of the packer.

During the life of the well, it may be necessary to perform various operations within the well which will include movements of the tubing within the Well. That is, it may be necessary to elevate and lower the tubing, or it may be necessary to entirely remove the same from the well. It has been found that this accumulation of mud and sediment above the packer will often cause the tubing to become jammed, making the abovementioned operations difficult or impossible to perform.

The present invention provides for removal of substantially all of the mud-laden fluid and particles of sediment from the chamber between the tubing and casing above the packer by a washing operation in addition to the conventional operation discussed above, this additional washing operation being accomplished by a ow of liquid downwardly through the chamber between the casing and tubing, which flow continues upwardly through the tubing to the slush pits. This downward flow of liquid will be in the direction in which the particles of mud and sediment in the casing would naturally move by gravity, and thus the removal of the mud particles from the casing will be more complete than in the conventional washing method using an upward flow of liquid. When the upward ow alone is used, it has been found that eddy currents of the lighterl washing uid will pass through the heavy mud and upwardly and out through the casing head outlets, leaving a considerable bulk of mud at the lower end of the casing, although it will appear from the dis` charge to the pits that the well is substantially cleansed of mud.

In Figure l, apreferred arrangement of casing head equipment is illustrated, the equipment disclosed being convenient for use in association with relatively deep wells. The casing head equipment is mounted upon a foundation' ring I2 which is cemented in position at the surface of the well. Extending downwardly into the well through the foundation ring is an outside string of casing I4, which string terminates at its lower end in a shoe I6 which, during the drilling of the well, is usually cemented in position.

The casing head is shown at I8, said casing head comprising two parts to accommodate a double string of casing. The casing head is provided with the usual side outlets 20 and 22, side outlet 20 being closed by means of a bull plug 24, while outlet 22 may connect with any desired system asy hereinafter described under control of the valve 26.

The well is shown equipped with a full string casing 28 which extends downwardly through the surface string I4 to the bottom of the well, said fullstring being secured at its upper end within the casing head in the usual mann'er, and being in communication with the interior of the casing head below the side outlets 28, 22. 'I'his full string of casing is provided at its lower end with a shoe 30, which is cemented in the bottom of the well" as shown at 32. The upper end of this full string casing is connected in to the casing head equipment in the conventional manner, so that fluid which passes upwardly therethrough may be discharged through the ow outlets 20, 22;

The tubing is designated 34 and extends downwardly through the casing head and through the full'string or casing 28 almost to the bottom 0f the well. The lower end of the tubing is connected with and carries a screen 36 in a manner hereinafter described. The tubing also carries a packer 38 in such manner that the tubing may be operated to seat the packer at the lower end of the full string in a manner which will be later described.

Rieferringto Figures 2 and 3, the screen 36 is shown provided with an area having a plurality of perforations 48 and includes an upper extension 42 which surrounds the lower end 34' of the tubing, the upper end of extension 42 terminating in a section 44 having an inwardly directed shoulder 46 which loosely embraces the lower end of the tubing.

'Ihe tubing is equipped adjacent the lower end thereof with an abutment 48 threaded to the outer wall of the tubing, said abutment being disposed within the screen extension 42 and being adapted to engage the undersurface of the section 44 when the tubing is being operated to lower the screen into the well as shown in Figure 3.

Fixed to the outer wall of the tubing 34 and spaced some distance above the annular abutment 48 is an annular ring 50, which has secured to the underside thereof the packer 38, the packer being of any appropriate material and surrounding the tubing 34 and having its lower end un secured. The annular ring 5I) and the packer 38 are positioned on the tubing above the extension 42 of the screen.

When the screen has been placed on the well bottom and the tubing 34 is lowered with respect thereto, as shown in Figure 2, the lower end of the packer 38 will engage the upper end 44 of the screen extension 42, and the weight of the tubing will compress the packer between the ring 50 and the upper end 44 of the screen, expanding the packer against the inner wall of the casing.

Secured to the lower end of the screen is a shoe 52 provided with a conical opening 54 in the lower end thereof, which constitutes a valve seat for a conical valve member 56 carried by the valve block 58. The block 58 is of considerable weight and is mounted upon a short rod 60 which passes through and is guided by central apertures in a pair of skeleton plates- 62 and 64 secured within the screen. These plates are of web-like construction, as shown in Figure 5, to permit ow of fluid therethrough. The upper end of the rod 68 carries a head 66 which suspends the valve block 58 by its own weight below the lower end of the screen during the lowering of the latter and during .the washing operations as hereinafter described. A spring 68 is positioned around the rod 60 above the valve block 56 and is adapted to engage the lower screen plate 62 when the valve is forced to its closed position as shown in Figure 2. 'Ihis spring, in addition to the weightof the valve block, will insure that the valve will not become stuck in closed position, and will cushion the engagement of the valve with its seat when the lower end of the valve block strikes weil bottom. The length of the rod 60 is such that the valve block will drop a substantial distance below the open ing 54 when the screen is being lowered into the well or during the washing operation as hereinafter described, to permit free ow of fluid inwardly and outwardly through the lower end of the screen. l

In washing and bringing in wells equipped with the foregoing apparatus, the well will be drilled in the usual manner and any number o! strings of casing will be set as desired, it being conventional to cement off the lower end ofeach cas- `ing and then drill through the cement to run the succeeding strings of casing, the cementl providing a blockade around the casing to prevent cratering of the well in the event of a blow-out.

The installation of the various strings of casing may include the installation of the full string of Casing` 28 which will be cemented at its bottom in the lower end of the well as at 32.

The portion of the full string of casing which passes through the oil bearing sands may then be perforated in any suitable manner, to provide a plurality of openings through which the oil may enter the casing.` In practicing the method of the present invention, it will be desirable to accurately locate the perforations 'i0 exactlyat the level with the oil bearing sands. To ascertain the proper-level equipment known in the art may be lowered down through the full string of casing 28 and observations of the formation may be taken to ascertain the position of the oil bearing sands. v

A gun type perforator will then be lowered into the well to the level'of `the oil vbearing sands, and a plurality of holes will be shot through the casing into the sands, 4-so that the oil may ow through the wall of the casing.

It will be understood that lduring the foregoing operations the well will be lled with muddv liquid and consequently no danger oi' a blow-out will exist.

After the perforations 'i0 have. been shot through the casing, the tubing 34 will be lowered therein, said tubing having suspended therefrom during the lowering operation, the packer 38 and the screen 36 positioned as shown in Figure 3. During the lowering of the tubing, the valvev block 58 will be suspended below the lower end o' the screen and shoe 52 to open the huid-way 54 as shown in Figure 3, the valve block being hung by the engagement of the head 5S with .the plate til. i y

The tubing Amay belowered into the well with conventional derrick equipment,V and vwhen the valve block 58 strikes the cement well bottom, the screen will `continue to move downwardly until the valve -seat 54 engages the valve member 56, and when this occurs, a slight jar will be noted at the surface ofk the wen. Ai this time the position of the tubing above the casing head will be carefullyL observed, and the tubing will be marked at the casing head to indicate when the valve member 5G has engaged its seat, it being apparent that any further downward movement of the tubing will result'inttbe telescoping of the tubing within the screen, thus expanding the packer. and the distance downwardly which the tubing must move to thoroughly expand the packer after seat 54 engages valve member 56 will be known before the apparatus is loweigd into the well.

The tubing will then be elevated to washing position,`a distance suicient for the valve block to drop to its lowermost position.as shown in Flgure"'3, and the tubing will then be cut and threaded at the proper point above theca'sirfg head I8-for the reception of a conventional tubing head 12. Thetubing head will be threaded to the tubing vas shown in Figure 4 a distance y above the casing head equal to the distance the tubing was elevated from theposition when the block 58 struck bottom and the valve 56.was on its seat, (the position when the slight jar was notedi to the position of Figure 3 with the valve member 56 in open condition, plus the distance through which. the'? tubing must be lowered after the valve member 56 engages its seat to expand the packer.

The tubing head 12 is of any well known type having a socket 14 adapted to engage within a bowl at the upper end of the casing head to seal the same around the tubing, and any suitable means suchas bolts may be provided to secure the tubing head to the upper end of the casing head after the operations hereinafter described have been completed. ltlowA control equipment such as a valve 'i6 and a control device 'I8 ofi the type disclosed in Patent No. 2,043,428, issued to been lled with mud, so that no danger of a blowout will have existed.

Threaded within the casing head above the sideI outlets 20, 22, as shownin Figure l is a stuffing box 80, comprising a packing retainerthreadf ed within the casing head carrying a quantity of Y. packing which engages the outer wall of the tub` ing, sald'packing being compressed within the retainer by a gland threaded inthe interior of the retainer. This stuiling box is adapted to form a seal between the casing heady and the tubing during -the washing operations hereinafter described.

The apparatus at the lower end of the tubing being inthe condition'disclosed. in Figure 3, with the tubing head 'i2 spacedabove the casing head as shown in Figure 4, the primary washing operation is initiated. During this operation. a bull plug closure is removed from the upper end of the flow control device 18 and'a line 82 is connected into said device in the place thereof, saidZ line` leading from a suitable pump to force water or other washing fluid downwardly through the tubing when the valve 16 is open. At th's time, the casing head side outlet valve 26 will be opened and a line 84 will be connected with the side outlet 22, said line leading to the slush pit.

The water or other iiuid pumped downwardly through the tubing will pass through the screen 36 and out through the bottom` passage 54 thereof into the lower end of the casing. and will then ascend between the inside of the casing andthe outside of the screen.v thus washing the same and removing the surrounding mud. This ilow of fluid will further ascend between the tubing and casing past the packer 38, which has not yet been set. and will pass upwardly through the casing head and out through the side outlet 22 through vthe line 84 to the slush pt. During this washing operation, the specific gravity of the mud in the well will be lowered, but control against a blow-out will be maintained by lthe valve 26 con,-f trolling against premature flow through the casing and the valve 16 controlling against reverse 6 ilow through the tubing, it being apparent that the stuillngbox willkmaintain a seal between the' tubing and casing at the casing head.

While a considerable portion of the mud within the well may be renioved by this primary washing operation, it is possible that the clear fluid will eddy upwardly through the mud, and will fail to thoroughly remove the same. In addition, this operation may not completely remove the mud and heavy particles which collect Vwithin the Cil chamber formed between the tubing and casing above the packer 38.

After the primary washing operation has been completed, the connections at the casing head will be reversed for vthe secondary washing operation. This reversal consists in connecting the line 82 with one leading to the slush pit, while a line from the washing uid pump is connected to the line 84. Water or other appropriate uid is then pumped inwardly through the side passage 22 to the casing head, which fluid flows downwardly through the casing between the inner wall of the same and the outer wall of the tubing, past the packer 38, after which it flows downwardly along the outside of the screen 36 thus washing the same. This ow of fluid passes upwardly through the passage 54 in the lower end -of the screen and ascends through the tubing, passing to the slush pit through the line 82.

It will be evident that this secondary washing operation will more thoroughly remove the mud from the interior of the casing and from outside the screen, as the downward direction of ilow will be-the same as the direction which the particles of sediment tend to move by gravity, and said particles will be cleared from the interior of the casing, particularly from the chamber between the casing and tubing above the packer 38.

Due to the fact that the downward area of flow through the casing will be somewhat greater than the internal area of upward ow within the tubing 34, the velocity of the liquid will be increased as it enters the lower end of the tubing, thus causing somewhat of a suction effect which will insure that any particles Within the lower end of the well outside and below the screen will be drawn upwardly through the tubin'g and conveyed to the slush pit.

During this secondary washing operation the well will be approaching a condition in which it will be ready to ow, but it will be apparent that control of the well will be maintained against premature flow through the casing and tubing by the valves 26 and 16 respectively, and a seal will be provided at the casing head between the tubing and casing by means of the stuing box 88.

After the well has been sufficiently washed, and it appears from the discharge to the slush pit that the well is ready to flow, the tubing will be lowered so that the valve block 58-will rest on the bottom of the well, the valve seat 54 engaging the valve member 56. The tubing will then be moved downwardly with respect to the screen to compress the packer 38 between abutments 58 and 4d as shown in Figure 2, and when this disposition of the parts is arrived at, the tubing head 12 will be positioned upon the casing head. The tubing head may then be secured to the casing head, after which the well may be flowed through the tubing und'er the control of the valve 16 and any other flow control devices associated with the casing head.

When the tubing is lowered to flowing position, as discussed above, the engagement of the valve seat 54 with the Valve member 56 will completely close off the lower end of the screen and thus the only channel of flow for the oil from the oil bearing sands will be inwardly through the perforations 18 in the casing 28, through the openings 4l) in the screen 36 and upwardly through the tubing.

It will be evident that the present invention provides a device and method permitting washing of the screen and well by a downward flow through the casing and an upward ow through the tubing, as well as washing by a `downward flow through the tubing and an upward ow through the casing. Furthermore, the construction of the screen and valve and parts which operate the same, makes possible washing by both an inward and outward flow through the lower end of the screen, yet also provides for the closing of the lower end of the screen in preparation for flowing the well, so that all of the oil will be taken into the tubing through the perforations in the screen.

It will further be evident that the method and apparatus disclosed herein provides for the conducting of the washing operations disclosed above while maintaining control of the well at all times, and at the same time, provides for the disposition of the flow control equipment to be used afterl the washing operations, immediately upon the casing head. The equipment used during the life of the well may as a result be compact and inexpensive.

It will be apparent that Various modifications may be made in the method and apparatus disclosed herein without departing from the scope of the present invention.

What is claimed is:

1. The method of bringing in a well of the type having a tubing therein with a screen at its lower end and a packer above the screen, which comprises washing the well with a current of liquid flowing downwardly through the tubing and upwardly outside the screen and past the packer, and preventing the accumulation of mud and the like around the tubing and above the packer by washing the well with a current of liquid flowing downwardly outside the tubing, past the packer and outside the screen and upwardly through the tubing, and setting the packer.

2. The method of bringing in a well of the type having a tubing with a screen at its lower end, and a packer above the screen, which comprises washing the well with a current of liquid flowing downwardly outside the tubing, past the packer, outside the screen and upwardly through a bottom opening in the screen, closing the bottom opening, and setting the packer and flowin g the well through the perforations in the screen and upwardly through the tubing.

3. The method of bringing in a well of the type having a tubing with a screen at its lower end, and a packer above the screen, which comprises washing the well with a current of liquid flowing downwardly through the tubing, and through a bottom opening in the screen, and upwardly outside the screen past the packer, and with a current flowing downwardly outside the tubing past the packer and outside the screen and through the bottom opening of the screen and upwardly through the tubing, closing the bottom opening and setting the packer, and owing the well through the vperforations in the screen and upwardly through the tubing.

KATHERINE T. CULLEN, Administratri of the Estate of Roy G. Cullen,

Deceased. 

